Stereolithography machine with cartridge containing a reservoir

ABSTRACT

A Cartridge ( 2; 2′; 2″ ) for a stereolithography machine ( 1 ), including a container ( 3 ) provided with an access opening ( 4 ), a reservoir ( 5 ) for containing a base material ( 6 ), liquid or pasty, suited to be solidified through exposure to a predefined radiation ( 7 ), said reservoir ( 5 ) being permanently associated with said container ( 3 ), feeding means ( 8 ) suited to feed said base material ( 6 ) from said reservoir ( 5 ) towards said container ( 3 ), characterized in that the bottom ( 9 ) of said container ( 3 ) is at least partially transparent to said predefined radiation ( 7 ) and is situated opposite said access opening ( 4 ).

The present invention concerns an interchangeable cartridge for astereolithography machine.

As is known, the stereolithography technique makes it possible toproduce a three-dimensional object by superimposing a plurality oflayers of a base material, liquid or pasty, that is solidified throughexposure to a predefined radiation, generally of the luminous type.

A stereolithography machine of the known type comprises a containersuited to contain the base material, the bottom of which is generallytransparent to the predefined radiation.

The machine also comprises means suited to emit said predefinedradiation, arranged under the container, which selectively solidify thelayer of base material that is adjacent to the bottom of the container.

The solidified layers are supported by a modelling platform, powered inthe vertical direction so that it is possible to arrange the lastsolidified layer adjacent to said layer of base material before itsolidifies.

The stereolithography machines of the known type pose the drawback thatthey require that the container be periodically topped up, so as torestore the level of the base material that is consumed during theprocess.

If said topping up operation is carried out manually, there is thedrawback that the operator must be exposed to the base material, withconsequent risks deriving from the possible toxicity of the latter.

According to a known variant embodiment, the topping up operation iscarried out automatically but in this case the stereolithography machinemust be provided with a feeding device, which involves a cost andrequires maintenance.

A further drawback of the machines constructed according to this variantembodiment derives from the fact that, when it is necessary to changethe base material, said feeding device must be washed in such a way asto avoid any contamination between the old and the new base material.

In any case, the machines described above pose the further drawback thatthe base material that remained in the container at the end of theprocessing cycle is exposed to the atmospheric agents, in particular tothe air and light of the surrounding environment, with the consequencethat it progressively deteriorates until it becomes unusable.

To avoid said deterioration, it is necessary to manually transfer theremained material into a container and keep it there until it is usedagain.

However, this operation poses drawbacks that are analogous to thosealready described with regard to the manual topping up of the container.

A further drawback posed by the stereolithography machines of the knowntype is connected to the fact that, during the processing cycle, thetransparent bottom of the container is exposed to the predefinedradiation and thus progressively becomes opaque.

Said opacifying action progressively reduces the effectiveness of theradiation, until it becomes necessary to replace the container.

The determination of the time when it is necessary to carry out saidreplacement requires a certain amount of expertise.

The difficulties related to the topping up and emptying of thecontainer, the periodical replacement of the container and the possiblewashing of the feeding system mean that a machine of the type describedabove is not suited to be used by an inexpert user.

Document EP 1852244 discloses a disposable liquid build material feedcartridge for use in solid imaging, while document JP H0215333 disclosesa stereolithography machine having a reservoir connected to an externalcontainer.

The present invention aims to overcome all the drawbacks which aretypical of the stereolithography machines of the known type describedabove.

In particular, it is a first object of the invention to eliminate theneed to periodically top up and/or empty the container.

It is a further object of the invention to avoid the need to wash thecontainer feeding system.

It is also the object of the invention to facilitate the replacement ofthe container when the bottom of the container has become opaque.

It is another, yet not the least object of the invention to avoid thedeterioration of the base material that has remained at the end of theprocessing cycle.

The above mentioned objects are achieved by a cartridge for astereolithography machine constructed according to claim 1.

Said objects are also achieved by a method for producing the cartridgeof the invention according to claim 14, as well as by astereolithography machine comprising the cartridge, according to claim15.

Further characteristics and details of the various aspects of theinvention are described in the corresponding dependent claims.

Advantageously, the stereolithography machine of the invention isparticularly suited to be used even by an inexpert operator like, forexample, an operator of the goldworking or dentistry sector.

The said objects and advantages, together with others which will behighlighted below, are illustrated in the description of a preferredembodiment of the invention which is provided by way of non-limitingexample with reference to the attached drawings, wherein:

FIG. 1 shows a side sectional view of the cartridge of the invention;

FIG. 2 shows the cartridge of FIG. 1 during use in a stereolithographymachine;

FIG. 3 shows a side sectional view of a variant embodiment of thecartridge of FIG. 1;

FIG. 4 shows a side sectional view of a further variant embodiment ofthe cartridge of FIG. 1.

The cartridge for a stereolithography machine that is the subject of theinvention, indicated as a whole by 2 in FIG. 1, comprises a container 3provided with an access opening 4.

The opening 4 is suited to allow a modelling platform 14 of astereolithography machine 1 to be inserted in the container 3 when thecartridge 2 is connected to said stereolithography machine 1, as shownin FIG. 2.

The cartridge 2 also comprises a reservoir 5 suited to contain a basematerial 6, liquid or pasty, suited to be solidified through exposure toa predefined radiation 7.

Preferably but not necessarily, said base material 6 is alight-hardening resin or a photopolymer and the predefined radiation 7is light.

Said reservoir 5 is permanently associated with the container 3 in sucha way as to form a single body with it.

Preferably, the container 3 and the reservoir 5 belong to a singlecontainment structure, which comprises an intermediate wall 16 thatseparates the container 3 from the reservoir 5.

The cartridge 2 comprises also feeding means 8 suited to transfer thebase material 6 from the reservoir 5 towards the container 3.

According to the invention, the container 3 has a bottom 9 that is atleast partially transparent to the predefined radiation 7 and issituated opposite the access opening 4 of the container 3.

The configuration of the access opening 4 and of the transparent bottom9 makes it possible to use said cartridge 2 in a stereolithographymachine 1 to replace the containers of the known type.

In fact, the transparent bottom 9 allows the passage of the predefinedradiation 7 to obtain the solidification of the base material 6contained in the container 3.

Furthermore, the access opening 4 allows the modelling platform 14 to beinserted in the container 3 and to be moved so that thestereolithography processing can be performed.

The reservoir 5 can be previously filled with base material 6 that,through the feeding means 8, is transferred into the container 3 as itis used during the processing cycle, so as to maintain the level of thebase material 6 in the container 3 substantially constant.

Therefore, the container 3 does not need to be topped up from theoutside, at least until the base material 6 in the reservoir 5 hascompletely run out, and thus one of the objects of the invention isachieved.

In particular, to advantage, the cartridge 2 described above does notrequire any topping up to be performed by the operator, nor automaticfeeding devices to be installed on the machine, which simplifies boththe stereolithography machine 1 and its use.

Furthermore, as the feeding means 8 are incorporated in the cartridge 2,there is no need to wash them if the base material for the processingcycle has to be changed, and thus another object of the invention isachieved.

In fact, the base material can be modified by simply replacing thecartridge 2 with another analogous cartridge containing the new basematerial.

Preferably, the reservoir 5 is provided with means suited to insulatethe base material 6 contained therein from the external environment.

Advantageously, said insulation effect makes it possible to protect thebase material 6 contained in the reservoir 5 from the air and/or lightof the surrounding environment.

Preferably, said insulation means comprise tight walls that delimit thereservoir 5.

In particular, the walls of the reservoir 5 are preferably opaque to thelight of the surrounding environment.

Regarding the feeding means 8, these are preferably configured in such away as to maintain the level of the base material 6 in the container 3within a predefined interval, independently of the level of the basematerial 6 present in the reservoir 5.

Advantageously, this makes it possible to constantly maintain the levelin the container 3 at an optimal value for processing, at the same timeavoiding possible leakages of the base material 6 through the container3.

Preferably, said feeding means 8 comprise a properly sized orifice thatconnects the reservoir 5 to the container 3.

In particular, said orifice can be configured in such a way as to allowthe spontaneous outflow of the base material 6 when the level in thecontainer 3 lowers and stop it once said level has been restored to itsinitial value.

The effect described above can be obtained, for example, by sizing theorifice in such a way as to exploit the different pressures acting onthe base material 6 present in the reservoir 5 and in the container 3,as well as capillarity through the orifice.

According to the variant embodiment of the invention shown in FIG. 3 andindicated by 2′ therein, said feeding means 8 comprise valve means 19suited to be controlled so as to allow or prevent the outflow of thebase material 6 from the reservoir 5 to the container 3 according to thelevel of the base material 6 present in the latter.

Preferably, said valve means 19 comprise an air valve suited to allowair to get into the reservoir 5.

According to a further variant embodiment illustrated in FIG. 4, thefeeding means 8 comprise a thrust device 18 suited to thrust the basematerial 6 from the reservoir 5 towards the container 3.

In particular, said thrust device 18 is configured so that its action isinhibited as long as the level of the base material 6 in the container 3remains within said predefined interval.

Preferably but not necessarily, said thrust device 18 is a pump.

Preferably, the cartridges 2′ and 2″ comprise power means 20respectively suited to supply power to the valve means 19 and the thrustdevice 18.

Preferably, said power means 20 comprise a power supply connector thatcan be associated with an analogous connector belonging to thestereolithography machine.

According to further variant embodiments of the invention, notillustrated in the figures, the feeding means 8 may comprise a holesuited to be closed and to allow the removable connection to thereservoir 5 of external control means configured so as to control theoutflow of the base material 6 towards the container 3.

Said external control means may comprise, for example, valve means or athrust device of the types described above.

In particular, the control means may belong to the stereolithographymachine 1.

Obviously, variant embodiments of the invention may comprise acombination of several feeding means selected among those describedabove.

Furthermore, in all the embodiments described above, the feeding means 8may comprise sensors 17 suited to monitor the level of the base material6 in the container 3 and to indicate any abnormal level.

In the last two embodiments, the sensors 17 can be operatively connectedto the valve means 19 and/or the thrust device 18 in such a way as tocontrol their action.

Preferably, the cartridge 2 also comprises means 10 suited to detect thelevel of the base material 6 contained in the reservoir 5.

Said detection means 10 make it possible to warn the operator that thebase material 6 contained in the reservoir 5 has run out, so that theoperator can replace the cartridge 2 when appropriate.

Therefore, the detection means 10 advantageously make it possible tofurther facilitate the use of the stereolithography machine 1.

Preferably, the detection means 10 are configured so as to emit anelectric signal that represents the level of the base material 6 in thereservoir 5.

Said electric signal is preferably transmitted to a device that isexternal to the cartridge 2 through connection means 11 that maycomprise, for example, a first connector suited to be removablyconnected to a second connector belonging to the stereolithographymachine 1.

The stereolithography machine 1 is preferably equipped with warningmeans, not represented herein but known per se, configured in such a waythat on receipt of said electric signal they can communicate to theoperator that the base material 6 contained in the reservoir 5 has runout.

Preferably, the cartridge 2 comprises also a door 12 movably associatedwith the access opening 4 of the container 3 in such a way that it canassume a closed position, shown in FIG. 1, and an open position, shownin FIG. 2.

Advantageously, closing said door 12 means making it possible toinsulate the contents of the cartridge 2 completely from the externalenvironment, for example during the periods when the cartridge 2 remainsunused, in such a way as to preserve the base material 6, achieving theobject to avoid its deterioration.

Still advantageously, said door 12 avoids any accidental contact betweenthe operator and the base material 6, to further advantage of the easeof use of the machine.

Preferably, the door 12 is motorized, so that it spontaneously assumesthe closed position.

Said motorization can be obtained, for example, through elastic means.

According to a variant embodiment, the motorization is obtained by meansof a closing device belonging to the stereolithography machine.

In this case, means suited to lock the door 12 in the closed positioncan be provided, which are suited to prevent the operator from openingthe door 12.

Said requisite can be met, for example, by configuring said lockingmeans so that they can be released only through a tool that isautomatically operated by the stereolithography machine 1 beforestarting the processing cycle.

In any case, the door 12 preferably comprises a shaped portion 12 asuited to define the ends of stroke corresponding to said open andclosed positions.

Preferably but not necessarily, the volume of the reservoir 5 isincluded between 1 cm³ and 50 cm³.

The volume indicated above corresponds to the quantity of base material6 necessary to produce a dental model of the type used in dentalmechanics.

Advantageously, a cartridge 2 with a reservoir 5 in the size indicatedabove can be used as a disposable cartridge, further simplifying the useof the machine for an unskilled operator, while at the same timelimiting the quantity of base material 6 to the indispensable minimum.

With regard to the transparent bottom 9 of the container 3, this ispreferably configured so that the energy, in the form of predefinedradiation 7, necessary to opacify it does not exceed 110% of the energy,in the form of the same predefined radiation 7, necessary to solidify aquantity of base material 6 corresponding to the volume of the reservoir5.

In this way, the duration of the transparent bottom 9 is adapted to thebase material 6 contained in the reservoir 5, with the advantage oflimiting the cost of the transparent bottom 9 and, thus, of thecartridge 2.

According to the method for producing said cartridge 2, the reservoir 5is preferably filled with base material 6 and the reservoir 5 and thecontainer 3 are sealed.

Said sealing effect is obtained by packaging the cartridge 2 in a tightpackage that is opened by the operator before starting the processingcycle.

According to a variant embodiment of the invention, said sealing effectcan be directly obtained through the walls of the cartridge 2.

In particular, the reservoir 5 can be filled through a hole that, oncethe filling operation has been completed, is closed in a tight andpreferably fixed manner.

Furthermore, the door 12 can be configured in such a way as to ensurethat the cartridge remains completely tight at least until the door isopened for the first time.

Operatively, the cartridge 2 is used on a stereolithography machinecomprising radiation emitting means 13 suited to emit the predefinedradiation 7 and a modelling platform 14 associated with power meanssuited to move the platform 14 along a movement trajectory X.

The machine is provided with removable connection means 15 suited tohouse the cartridge 2 in an operating position that is schematicallyillustrated in FIG. 2.

Advantageously, said connection means 15 allow the cartridge 2 to beeasily installed on the stereolithography machine 1, as well as to beeasily removed once the cartridge 2 has been used up.

In particular, the operating position defined by the connection means 15for the cartridge 2 is such that the transparent bottom 9 of thecartridge is arranged along the trajectory of said predefined radiation7 and that the access opening 4 is arranged along said moving trajectoryX of the platform 14.

Preferably, the connection means 15 are provided with sensors, notillustrated in the figures but known per se, suited to detect thepresence of the cartridge 2 and to indicate, if necessary, anypositioning defect, thus further improving ease of use.

Once the cartridge 2 has been positioned on the machine 1, the door 12of the container 3 is opened, preferably automatically, in order toallow the modelling platform 14 to enter the container 3.

Successively, the radiation emitting means 13 and the modelling platform14 are operated in such a way as to obtain the three-dimensional object,according to the stereolithography methods known per se.

At the end of the processing cycle, the modelling platform 14 and,together with it, the finished object, are extracted from the container3.

Preferably, the movable door 12 of the container 3 is closed in such away as to protect the base material 6 remained in the cartridge 2 fromthe atmospheric agents, so that it can be used again at a later moment.

The stereolithography machine 1 can be configured so that it warns theoperator if the level of the base material 6 present in the reservoir 5is below a predefined threshold before starting a successive processingcycle.

According to a variant embodiment, the stereolithography machine 1 isconfigured so that it can calculate the quantity of base material 6necessary to make the object, comparing it with the quantity of basematerial 6 available in the reservoir 5.

If the quantity of base material 6 available in the reservoir 5 is notsufficient, the stereolithography machine 1 warns the user.

The above clearly shows that the cartridge described above achieves allthe set objects.

In particular, the presence of the reservoir and of the feeding meanseliminates the need for the operator to periodically top up and/or emptythe container of the cartridge.

Furthermore, easy connection and removal of the cartridge to/from themachine facilitate replacement when the bottom of the container becomesopaque.

Said ease of use is further enhanced by the presence of means fordetecting the level of the base material present in the reservoir.

Ease of use is also favoured by the fact that it is not necessary towash the container feeding system in the case where the base materialmust be changed, as the feeding system is incorporated in the cartridge.

Therefore, it is sufficient to replace the cartridge with an analogouscartridge containing the new base material.

Furthermore, the possibility to close the access opening of thecartridge of the invention makes it possible to preserve the materialcontained therein, preventing its untimely deterioration.

The invention claimed is:
 1. A stereolithography machine comprising: acartridge comprising: a container provided with an access opening and abottom that is transparent to a predefined radiation; a reservoircontaining a liquid or paste base material suited to be solidifiedthrough exposure to the predefined radiation, said reservoir beingpermanently associated with said container to form a single body; andmeans for feeding incorporated into the cartridge and suited to feedsaid base material from said reservoir towards said container; whereinsaid stereolithography machine further comprises: means for emittingradiation suited to emit the predefined radiation to travel through thetransparent bottom; a modelling platform associated with power means tomove said platform along a movement trajectory (X) and means forremovably connecting said cartridge in an operating position such thatsaid transparent bottom is arranged along the trajectory of saidpredefined radiation and such that said access opening is arranged alongsaid movement trajectory (X) of said modelling platform.
 2. Thestereolithography machine according to claim 1 wherein the bottom ofsaid container is at least partially transparent to said predefinedradiation and is situated opposite said access opening.
 3. Thestereolithography machine according to claim 2, wherein said reservoirfurther comprises means for insulating the base material containedtherein from the external environment.
 4. The stereolithography machineaccording to claim 2, wherein said means for feeding is configured tomaintain the level of said base material contained in said containerwithin a predefined interval.
 5. The stereolithography machine accordingto claim 2, wherein said means for feeding further comprises a valvecontrolled to allow or prevent the outflow of said base material fromsaid reservoir to said container.
 6. The stereolithography machineaccording to claim 2, wherein said means for feeding further comprises athrust device suited to thrust said base material towards saidcontainer.
 7. The stereolithography machine according to claim 2,further comprising means for detecting suited to monitor the level ofsaid base material contained in said reservoir.
 8. The stereolithographymachine according to claim 7, wherein said means for detecting isconfigured to emit an electrical signal that represents the level ofsaid base material contained in said reservoir, and further comprisingconnection means to allow the transmission of said electrical signal toa device external to said cartridge.
 9. The stereolithography machineaccording to claim 2, further comprising a door movably associated withsaid access opening in such a way as to assume at least one openposition and at least one closed position for said access openingcompletely insulating the content of the cartridge from the externalenvironment when arranged in said closed position.
 10. Thestereolithography machine according to claim 9, wherein said door ismotorized so as to spontaneously assume said closed position.
 11. Thestereolithography machine according to claim 2, wherein said reservoirhas a volume included between 1 cm³ and 50 cm³.
 12. Thestereolithographv machine according to claim 1 which further comprisescontrol means suited to be connected to said feeding means in order tooperate them in such a way as to control the outflow of said basematerial toward said container.
 13. The stereolithographv machineaccording to claim 1 wherein the cartridge comprises a connectionelement for removable connection to the stereolithography machine. 14.The stereolithography machine according to claim 1 wherein said feedingmeans is adapted to provide a layer of base material in contact withsaid transparent bottom.
 15. The stereolithography machine according toclaim 9 wherein the cartridge comprises locking means to lock said doorin said closed position.
 16. The stereolithography machine according toclaim 9 wherein said door is configured so as to keep said cartridgecompletely tight at least until the first opening of said door.
 17. Thestereolithography machine according to claim 1 wherein said connectionmeans is provided with sensors to detect the presence of said cartridge.18. The stereolithography machine according to claim 1 wherein saidcartridge comprises a door movably associated with said access openingin such a way as to assume at least one open position and at least oneclosed position for said access opening, said stereolithography machinefurther comprising an actuator for opening said door.
 19. Astereolithography machine comprising: a cartridge comprising a containerhaving an access opening and a bottom that is transparent to apredefined radiation, a reservoir containing a liquid or paste basematerial suited to be solidified through exposure to the predefinedradiation, said reservoir being permanently associated with saidcontainer to form a single body, and a feed device incorporated into thecartridge configured to feed said base material from said reservoir intosaid container; a radiation source to emit the predefined radiation totravel through the transparent bottom; a modelling platform associatedwith a drive system connected to move said platform along a movementtrajectory (X); and a housing for removably connecting said cartridge inan operating position such that said transparent bottom is arrangedalong the trajectory of said predefined radiation and such that saidaccess opening is arranged along said movement trajectory (X) of saidmodelling platform.
 20. The stereolithography machine according to claim19 which further comprises a controller connected to said feed device asto control the outflow of said base material toward said container. 21.The stereolithography machine according to claim 19 wherein thecartridge comprises a connector for removable connection to thestereolithography machine.
 22. The stereolithography machine accordingto claim 19 wherein said feed device is configured to provide a layer ofbase material in contact with said transparent bottom.
 23. Thestereolithography machine according to claim 21 wherein said connectorincludes sensors to detect the presence of said cartridge.
 24. Thestereolithography machine according to claim 19 wherein said cartridgecomprises a door movably associated with said access opening in such away as to assume at least one open position and at least one closedposition for said access opening, said stereolithography machine furthercomprising an actuator for opening said door.
 25. The stereolithographymachine according to claim 19 wherein the bottom of said container is atleast partially transparent to said predefined radiation and is situatedopposite said access opening.
 26. The stereolithography machineaccording to claim 19 wherein said reservoir further comprisesdelimiting walls to insulate the base material contained in thereservoir from the external environment.
 27. The stereolithographymachine according to claim 19 wherein said feed device is configured tomaintain the level of said base material contained in said containerwithin a predefined interval.
 28. The stereolithography machineaccording to claim 19 wherein said feed device further comprises a valveconnected to allow or prevent the outflow of said base material fromsaid reservoir to said container.
 29. The stereolithography machineaccording to claim 19 wherein said feed device further comprises athrust device suited to thrust said base material toward said container.30. The stereolithography machine according to claim 19 furthercomprising a detector positioned to monitor the level of said basematerial contained in said reservoir.
 31. The stereolithography machineaccording to claim 30, wherein said detector is configured to emit anelectrical signal that represents the level of said base materialcontained in said reservoir, and further comprising a connector to allowthe transmission of said electrical signal to a device external to saidcartridge.
 32. The stereolithography machine according to claim 24,wherein said door insulates the content of the cartridge from theexternal environment when arranged in said closed position.
 33. Thestereolithography machine according to claim 24, wherein said door ismotorized so as to spontaneously assume said closed position.
 34. Thestereolithography machine according to claim 24 wherein the cartridgecomprises locking means to lock said door in said closed position. 35.The stereolithography machine according to claim 24 wherein said door isconfigured so as to keep said cartridge tight at least until the firstopening of said door.